How to reset the GUI - without using the menu...?
Approach 1 (recommended)
Open the directory where Blender is installed and type cmd in the address bar and press enter. Then run the following command to start Blender and set the Resolution Scale to its default value.
.\blender.exe --python-expr &quot;import bpy; bpy.context.preferences.view.ui_scale = 1.0&quot;

If auto-saving for the preferences is disabled, you need to manually save them.

Open the preferences (Edit &gt; Preferences).
Click on the hamburger icon in the lower left corner.
Select Save Preferences.


Approach 2
This will completely reset Blender to its factory default settings.
Open the directory where Blender is installed and type cmd in the address bar and press enter. Then run the following command to start Blender with the factory settings.
.\blender.exe --factory-startup

Next you need to manually save the settings.

Open the preferences (Edit &gt; Preferences).
Click on the hamburger icon in the lower left corner.
Select Save Preferences.